Rule number 1.
Pay for nothing, (except hosting,). Learn EVERYTHING yourself, no matter how much someone says "buy this, i learnt the hardway, but here you can have a fast ride to the top". If you learn it, (even PHP or Ruby On Rails or some programming) and how to make a website etc etc, then if it all fucks up, you haven't spent anything but have learnt HEAPS! You are in a much better position than someone who has spent money and it didn't work. The cool thing is that with the net it is actually possible to make money off pure knowledge and hardwork with no necessary capital investment (except hosting).
RULE NUMBER 2.
sorry to be cliche, but reffer to rule number 1.